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5.6 Online Program Change for Redundancy
5.6.2 Program Change While CPU is Running
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5.6.2 Program Change While CPU is Running
Data are written to both systems while CPU is running, in the following cases:
• Online program change
• Writing files in RUN
• T/C set value change
Refer to the following manual for details on the above operations.
QCPU User's Manual (Function Explanation, Program Fundamentals)
(1) Operations When Changing Programs While CPU is running
When changing the program of the control system CPU module during RUN in the
backup mode, the same program will be written to the standby system CPU module.
Even if a stop error occurs in the control system during the online program change
and system switching occurs, the online program change to both systems will
continue.
(2) Procedure for Writing to the Control System and Standby System
When performing the online program change to the control system CPU module by
GX Developer, regardless of the connection route.
When the online program change is performed to the control system CPU module,
data will be written to the control system and standby system CPU modules.
Diagram 5.65 shows the operation in the case of program change in ladder mode
during RUN.
(The program change in ladder mode during RUN is executed in the order (1) and
(2).)
Diagram 5.65 Procedure for Writing to Control System and Standby System When Program Is Changed during CPU RUN
Control system
Standby system
Execute writing during
RUN to new control
CPU module
Write during
program A
running
1)
after completing writing to control
system CPU module, write to
standby system CPU module
2)
Program memory (Program A)
Y1A0
Addition
INC D0
DEC D10
Program memory (Program A)
Y1A0
Addition
INC D0
DEC D10